Springfield, Ill. — Presumptive Democratic presidential nominee Barack Obama and Sen. Joe Biden, D-Del., today made their first public appearance since Obama announced Biden as his running mate.

Obama made the announcement through a text message to supporters at about 3 a.m. Saturday. Many supporters who signed up to for the text message reported never receiving it.

On the steps of the Illinois state capitol where he announced his candidacy for president in February 2007, Obama introduced Biden to a crowd of more than 30,000 people, calling him “one of the finest public servants of our time.”

Obama praised Biden’s work to promote women’s rights, affordable college tuition and raising the minimum wage, and highlighted his background in foreign policy.

In his first speech as the presumptive Democratic Vice Presidential nominee, Biden, who has 35 years of experience in Congress, called presumptive Republican presidential nominee John McCain a friend and a great legislator, but said he doesn’t believe McCain is qualified to lead the nation.

“These times require more than a good soldier. They require a wise leader,” he said. “You can’t change America when you support Bush’s policies 95 percent of the time.”

McCain’s campaign has released an advertisement criticizing Biden for past remarks that seemed to express opposition to Obama and support for McCain.

But Obama said Biden’s willingness to speak his mind makes him a good running mate.

“I know that Joe Biden will give us some real straight talk,” he said. “He’s still that scrappy kid from Scranton (Penn.), who beat the odds.”

Sweltering heat did not deter tens of thousands of supporters from coming to see the appearance, but paramedics responded to many heat-related injuries within the crowd.

Following the rally, firefighters opened street hydrants, passed out bottled water and allowed water to spray from their fire trucks to offer relief.

Immediately following the event, officials could not confirm how many people received medical attention.